Manufacturing process of cadmium sulfide, selenide, telluride photoconducting cells



Sept. 8, 1953 F. F. GANS 2,651,700 MANUFACTURING PROCESS OF CADMIUM SULFIDE, SELENIDE, TELLURIDE PHOTOCONDUCTING CELLS Filed Nov. 10, 1952 Patented Sept. 8, 1953 IWANUFACTURING PROCESS OF CADMIUM SULFIDE, S-ELENIDE, TELLURIDE PHOTO- CONDUCTING CELLS Francois F. Gans, Paris, France Application November 10, 1952, Serial N 0. 319,650

' In France November 24, 1951 Claims. (01. 20163) The present invention relates to a process for these drawbacks are avoided by producing, the production of photoelectric cells, and more through compression and sintering of a very which may possess any size. It has been noticed that the cadmium sulfide In order to produce the above mentioned cell, becomes the more elncient as suitably selected the following procedure is used. impurities called activators are added in small The mixture of cadmium sulfide and of the acare very numerous and it may be mentioned for several days into a very fine powder (by such copper, silver, gold, lead and nickel, etc. an apparatus as a ball-mill) so that the grains It has also been noticed that cadmium selenide of the powder should have a diameter of under and cadmium telluride present similar proper- 5 or thereabout.

ties. to give a clearer idea of the nature In order The described procedure relates to cadmium and contents of the activating powders, three sulfide but it is to be understood that it applies examples are given hereinafter.

equally to both cadmium selenide and cadmium Example No. 1: Cells of great inertia in the telluride cells, without departing from the spirit neighbourhood of one second and of sensibility of the invention. in the neighbourhood of 5 to 10 a./lm. (amperes In order to produce cadmium sulfide photoconper lumen) ducting cells, a standard process is to dip a cadeds 1000 mlum sulfide crystal, or a slip of such material Gus 4 as glass on which a layer of cadmium sulfide has cdse 20 been evaporated, into a homogeneous mixture Te 20 of cadmium sulfide and of the chosen activator or activators, reduced into a fine powder. Then Example No. 2: Ordinary cells of average inerthe vessel containing the powder is heat d t tia and sensibility (inertia of about 1/100 second a. suitable temperature of 500 c, Thermodifiuand sensibility of about one ampere per lumen) sion produces an equilibrium between the aceds 1000 mm of the metal, or of the evapso cus ::::::::::::::::::::::::::::"7:" 25 Orated layer n he one hand, and of t Nick 5 re on the Other. case fill:-

Such processes are not without drawbacks. r v The crystals ar e fairly difficult to prepare, their xample N0. 3: Cells of low inertia of about size is seldom large enough, seldom more tha 1/1000 second and sensibility of about 0.1 to 0.5

' a./lm.

small, less than one millimeter, and their brit- Cds tleness makes them difilcult to handle. Gus g The dimensions of the evaporated layers may n 25 be large, but they are very thin; they take a long 40 'me to prepare, and, therefore, their price is Once the powder has been obtained, a cerhig Besides, the evaporated layers have a tain quantity of said powder, 0 1 to l gramme, 1s lacunary structure and, owing to this structure, tak t a houslng 3, havlng surface of few varies according to the illumination, a paras1tic pressure of over 2 tons per cmfi.

is not regular, and it results into a parasitic noise cylinder of the press, communicates through a According to the process the present invento heat at a temperature between 550 and 600 tion relates to, process which is disclosed in rela- C. the tablet of powder while the pressure is tion with the figure which represents a press, being applied to it.

7 The electrodes are brush painted with a conof not greater than about It, and compressing *ducting silver lacquer such as the one sold by and heating said powder under a pressure of the firm Degussa under N0. 200. about 2 tons per square centimeter and a tem- The sensibility of the cells depends on the perature of about 550 C. to obtain said powder pressure as shown by the following table which 5 in tablet form, said tablet adapted to be provided gives in megohms, the resistance of two cells with conducting electrodes. manufactured with the powder of Example N0. 2. 2. A process as in claim 1 wherein said pressure is about tons per square centimeter and said Cell I compressed up to 8 tons per cm. Cell 11 compressed up to 15 tons per 0111. temperature is between about 550 C. and 600 C.

10 3. A photoconducting cell comprising particles of a photoconducting material selected from the Illumination in lux 200 500 1,000 I class consistlng of cadmium sulfide, cadmium resistance of Gen 1 in selen de and cadmium tellu ride and an activator 100 so 15 2.4 L6 1- therefor, ground to a particle size of less than about 5 ,u compressed under a pressure of more than about 2 tons per square centimeter and heated to a temperature of above 550 C.

ohms resistance of cell 11 in meg- 15 ohms 4. 5 1 0. 45 0.16 0.12 041 What I claim is: l. A process for the production of photoelect' fi izzggggg of 01mm 3 provlded Wlth contr1c cells containing a photoconductmg material 20 The Structure of claim 4 in which the elec selected from the class consisting of cadmium rode t1n s o e onductin lac er sulfide, cadmium selenide and cadmium telluride t s are Goa g f m tau 0 g qu comprising mixing said photoconducting material N Q GANS- with activators therefor, grinding the mixture to obtain a powder having a particle diameter No references t 

1. A PROCESS FOR THE PRODUCTION OF PHOTOELECTRIC CELLS CONTAINING A PHOTOCONDUCTING MATERIAL SELECTED FROM THE CLASS CONSISTING OF CADMIUM SULFIDE, CADMIUM SELENIDE AND CADMIUM TELLURIDE COMPRISING MIXING SAID PHOTOCONDUCTING MATERIAL WITH ACTIVATORS THEREFOR, GRINDING THE MIXTURE TO OBTAIN A POWDER HAVING A PARTICLE DIAMETER 